The genus , harbouring 293 species/subspecies, constitutes a phylogenetically incoherent group. In the absence of reliable means for grouping known species into distinct clades, restricting the placement of new species into this genus has proven difficult. To clarify the evolutionary relationships among species, 352 available genome sequences from the family were used to perform comprehensive phylogenomic and comparative genomic analyses. Four phylogenetic trees were reconstructed based on multiple datasets of proteins including 1172 core proteins, 87 proteins conserved within the phylum Firmicutes, GyrA-GyrB-RpoB-RpoC proteins, and UvrD-PolA proteins. All trees exhibited nearly identical branching of species and consistently displayed six novel monophyletic clades encompassing 5-23 species (denoted as the Simplex, Firmus, Jeotgali, Niacini, Fastidiosus and Alcalophilus clades), interspersed with other species. Species from these clades also generally grouped together in 16S rRNA gene trees. In parallel, our comparative genomic analyses of species led to the identification of 36 molecular markers comprising conserved signature indels in protein sequences that are specifically shared by the species from these six observed clades, thus reliably demarcating these clades based on multiple molecular synapomorphies. Based on the strong evidence from multiple lines of investigations supporting the existence of these six distinct ' ' clades, we propose the transfer of species from these clades into six novel genera viz. gen. nov., gen. nov., gen. nov., gen. nov., gen. nov. and gen. nov. These results represent an important step towards clarifying the phylogeny/taxonomy of the genus .